Individuals with type 1 diabetes mellitus (T1DM) may be more susceptible than the general population to develop eating disorders. In addition to the above categories, people with T1DM have the opportunity for a unique inappropriate compensatory behavior, namely intentional insulin omission for the purpose of preventing weight gain. This behavior is recognized as either an inappropriate compensatory feature of bulimia nervosa or as a purging disorder after binge eating, or a component of other specified feeding or eating disorder when insulin omission occurs in the absence of binge eating.

Epidemiology

The prevalence rate of eating disorders among adolescent with T1DM, differ according to characteristics of the study population, such as age range, whether males were included or only females and according to the specific eating disorder studied. In general no difference in the prevalence of anorexia nervosa was demonstrated in individuals with T1DM compared with a control group[2], however, a 2.4 times risk of developing bulimia nervosa compared to healthy adolescents was demonstrated [3].

The prevalence of intentional insulin omission has been shown to increase with age from 2% among girls aged 9-13 years, 11% among girls aged 12-19 years, 34% among teenagers aged 16-22 years to 40% among young women aged 18-30 year old.[4]

Predisposition for Developing Eating Disorders

Several factors involving the premorbid status as well as chronic disease management were identified as risk factors for developing eating disorders. These include personal factors, family factors, and disease associated factors.

Personal factors: Girls who reported ever being overweight endorsed more disordered eating attitudes and behavior [5]. An increase in BMI from adolescence to adulthood and higher levels of weight dissatisfaction are associated with unhealthy weight control and disordered eating [6]. Lower self-esteem was associated with disturbed eating behavior in girls with T1DM[7]. Individuals with T1DM who are perfectionistic and who possess borderline personality characteristics were more likely to be weight preoccupied and to engage in medically risky behavior [8].

Family factors: Eating disturbances in adolescent girls with T1DM were found to be associated with more family dysfunction; specifically, eating disturbances are associated with less support, poorer communication and less trust in the relationships of girls with their parents, and impaired mother-daughter relationships [9]. The prevalence of families with a parent engaging in behavior to lose weight and/or making negative comments about eating or weight was found to be higher in families of girls with eating disorders than those without eating disorders [10].

Disease associated factors: Intensive insulin treatment conveys an increased risk of weight gain, which causes negative feelings about weight and shape and fear of further weight gain, leading to insulin restriction for weight regulation. Furthermore, diabetes management imposes dietary restraint which may lead to yearning and craving "forbidden foods", and result in binging, without administration of the appropriate insulin dose.[11] In addition, the strict dietary regimen that is a component of T1DM management is associated with recurrent hypoglycemic episodes. Hypoglycemia is accompanied by intense hunger, eating large amounts and by eating sweetened food and drinks. This vicious cycle of dietary restriction, over-eating, and guilt is similar to that experienced by individuals with bulimia nervosa[12].

Clinical Signs of Eating Disorders among Adolescents with T1DM

Eating disorder behaviors are often well hidden, and a high index of suspicion is needed for diagnosis. Clinical signs that should alert health care providers to the possibility of eating disorders in adolescents with T1DM include poor glycemic control with significantly higher HbA1c level [13] and recurrent episodes of diabetic ketoacidosis. Other signs include frequently missed medical appointments, refusal to be weighed, preoccupation with appearance, tendency to vegetarianism, calculating caloric values of foods and weighing foods.

Apparently, due to the availability of insulin omission as a weight loss strategy, females with T1DM are less likely to use extreme unhealthy weight control behavior like vomiting, laxatives or diuretics, skipping meals or fasting, compared to their peers without diabetes [14]. Depression may serve as a cause of susceptibility for developing disturbed eating behavior. Indeed, in a study among girls with T1DM who were interviewed for symptoms of depression and disturbed eating behavior at baseline and 5 years later Eating Disorder Examination scores were significantly higher in girls with depression.

Diagnosing Eating Disorders in Adolescents with T1DM

General diagnostic questionnaires for detecting eating disorders are not appropriate for individuals with T1DM, as such questionnaires do not identify eating disorder behavior that are unique to T1DM, such as insulin omission [15]. Moreover, the means of diagnosing disturbed eating in the general population, may not be adequate for people with diabetes, since some behavior considered as disturbed eating may in fact be components of the regular diabetes self-care regimen [16]. The revised Diabetes Eating Problem Survey (DEPS-R) is a 16-item diabetes-specific self-report measure of disordered eating that was designed specifically for people with diabetes [15]. Table 1 shows the mSCOFF questionnaire which is a simple 5 item screening tool that is reliable and valid, and that can easily be used by diabetologists during a follow-up visit. Using data mining methods a clinical prediction model that provides a decision support system for the detection of intentional insulin omission for weight loss in adolescent females with T1DM was developed[17]. The model is based on distinguishing the pattern of HbA1c levels recorded for patients with intentional insulin omission from that of others with T1DM. After a period of apparently stable glycemic control, the onset of insulin omission is characterized by both high HbA1c levels and wide fluctuations from visit to visit.

Table 1: Modified SCOFF questionnaire

• Do you make yourself Sick because you feel uncomfortably full?

• Do you worry you have lost Control over how much you eat?

• Have you recently lost more than One stone in a 3 month period?

• Do you believe yourself to be Fat when others say you are too thin?

• “Do you ever take less insulin than you should?”

One point for every “yes” ; a score of ≥ 2 indicates a likely case of anorexia nervosa or bulimia

Morbidity and Mortality

Eating Disorders result in poor metabolic control and cause short and long-term complications. Increased rates of hypoglycemia with coma, events of diabetic ketoacidosis and hospitalization were higher, among those with eating disorders[18].

Long-term complications are associated with the duration of severe insulin omission. In a 4 year follow-up study, 86% of girls with T1DM and severe eating disorders developed retinopathy, compared to 24% of girls without eating disorders[13]. In a 10 year follow-up study of females with T1DM, 25% of those who reported insulin omission had nephropathy, compared with 10% of those who did not [19]. Finally a mortality rate of 34.6 per 1,000 person years was reported in girls with both T1DM and an eating disorder compared to 2.2 per 1,000 person years in girls with T1DM [20].

Treatment

Treatment of eating disorders in people with T1DM is challenging, especially since the clinical improvement achieved with insulin treatment is associated with weight gain. Treatment involves a complex interplay of psychosocial and biological aspects and requires a multidisciplinary team. Treatment should focus on diabetes management with realistic blood glucose targets, and dietary treatment focusing on healthy choices and low calorie alternatives with a high satiety index. Treatment with insulin pump was postulated as a means of enabling more physiological treatment to adolescents with T1DM compared with multiple daily injections. Patients with insulin pumps require less insulin and thus gain less weight. Furthermore, the occurrence of hypoglycemic episodes is decreased, and thus the need to consume extra calories decreases. A recently published multicenter study demonstrated a decrease in disturbed eating behavior, in youth with T1DM, 6 months after pump initiation[21]. Moreover, among adolescent girls with T1DM and ED, the mean HbA1c level was significantly lower in those who were treated by insulin pumps than in those who were treated with multiple daily injections[22].

Children and adolescents with T1DM are at increased risk to develop depression and anxiety compared to the general population and those with T1DM and eating disorders have a three-fold risk to develop depression [23]. This overlap in eating behavior and mood highlights the importance of treating depression as a means of treating eating disorders. Several modes of treatment have been studied, including: individual treatment, family treatment, group treatment, and hospitalization.

In summary:

Eating disorders, in particular deliberate insulin omission as a weight loss strategy are common among adolescents and young adults with T1DM. Diagnosis of eating disorders in individuals with diabetes is difficult, since eating disorder behaviors are often well hidden. Weight loss that is related to deteriorated glycemic control and recurrent diabetic ketoacidosis should raise suspicion. Early diagnosis is essential, as the combination of eating disorders and diabetes is associated with increased morbidity and mortality.